Memory and Storage Computer Technology K. Steere

RAM Random Access Memory Measured in Megabytes When you power off – information stored here is gone More RAM means you can open more programs Most common memory—found in printers and other devices

ROM Read Only Memory Data has been prerecorded Once data has been written onto a ROM chip, it cannot be removed and can only be read

Memory and Storage Capacity Approximate values: b or Bit – 1 binary digit—smallest unit B or Byte – 8 bits KB or Kilobyte – 1 thousand bytes MB or Megabyte – 1 million bytes GB or Gigabyte – 1 billion bytes TB or Terabyte – 1 trillion bytes

Storage Devices 3.5" Floppy Disk Drive Zip Drive CD-R and CD-RW DVD-R and DVD-RW Hard Disk Drive

Storage Devices 1.44 MB 100 or 250 MB CD-680 MB Up to 100 GB DVD-4 to 17 GB

3½" Floppy Disks High Density 1.44 MB Portable Magnetic storage Formatting – readies disk for use

Hard Drives Store anywhere from 10 megabytes to several gigabytes Stored inside the computer Magnetic storage

Zip Drives 100 or 250 MB Files that have been compressed are called ZIP files Usually end with a.zip extension

Compact Discs – Optical Storage CD-ROM (compact disk ROM) CD-R (compact disk-recordable) CD-RW (compact disk-rewritable) DVD-ROM (digital video disc-ROM) DVD-R (digital video disk-recordable) DVD-RW (digital video disk-rewritable)

Compact Disks 680 MB Speeds (e.g., 40X) CD-ROMCD-RCD-RW Retrieve dataXXX Write (save)XX Modify & saveX

Digital Video Disks 4.7 – 17 GB Speeds (e.g., 16X) Movies and Multimedia Presentations DVD-ROMDVD-RDVD-RW Retrieve dataXXX Write (save)XX Modify and saveX

Data Disk Rules Keep away from extreme temperatures. Keep disks and CDs in storage cases. Keep disks away from magnetic forces.

Formatting Prepares disk to be able to store data. Makes sure recording areas are reliable. Marks bad areas to avoid trying to save there

Write-protected Protects existing information from being deleted or saved over